added MongoDB 2.4 2d indexes

[jsaak]

# Create a new index.
#
# @param [String, Array] spec
#   should be either a single field name or an array of
#   [field name, direction] pairs. Directions should be specified
#   as EM::Mongo::ASCENDING, EM::Mongo::DESCENDING, EM::Mongo::FLAT2D, EM::Mongo::SPHERE2D
#
#   Note that MongoDB 2.2 used 2d flat indexes and called them geo, MongoDB 2.4 has 2d and 2dsphere indexes
#   EM::Mongo::GEO2D is kept for backward compatiblity and is creating a flat 2d index

[bcg]

@jsaak interested in taking over em-mongo?

[jsaak]

sure

[bcg]

Ok, @jsaak start merging!

[jsaak]

i was thinking about the future of em-mongo and i think the best would be to merge with the official ruby driver mongo is changing fast, and there is really no need for another driver, if we can somehow make the official driver to support EM or even EM-SYNCHRONY just like the redis driver

what do you think?

[bcg]

Fine by me. Last time I looked into this (years ago), it looked like it would be pretty disruptive to the official driver codebase, so I'd get some high level clearance before you spend all that time working on it.

[jsaak]

do you want me to push new versions? if so, i need access to rubygems my rubygems account name is "jsaak" too

[bcg]

@jsaak done. give it a try.